Liquid fuel injection pumps for internal combustion engines



United States Patent 3,194,224 AIR COOLED INTERNAL CGMBUSTION ENGINE LeoJ. Leclitenberg, Elm Grove, Robert K. Catterson, Brookfield, and JosephV. Reichenbach, Milwaukee, Wis., assignors to Briggs & StrattonCorporation, Milwaukee, Wis., a corporation of Delaware Originalapplication June 27, 1962, Ser. No. 205,658, now Patent No. 3,118,433,dated Jan. 21, 1964. Divided and this application Oct. 3, 1963, Ser. No.313,546

(Ilairns. (Cl. 123-119) This invention, like that of the application ofLeo J. Lechtenberg, Serial No; 205,658, now Patent No. 3,118,433, ofwhich this is a division, relates to internal combustion engines andrefers more particularly to single cylinder air-cooled engines of thetype widely used on power lawn mowers.

The object of this invention is to provide a simplified and morepractical carburetor for engines of the type indicated, particularlyfrom the standpoint of assuring continued freedom of adjustment of itsthrottle valve and choke valve, even in dusty and sandy surroundings.

With the above and other objects in view which will appear as thedescription proceeds, this invention resides in the novel construction,combination and arrangement of parts substantially as hereinafterdescribed and more particularly defined by the appended claims, it beingunderstood that such changes in the precise embodiment of thehereindisclosed invention may be made as come within the scope of theclaims.

The accompanying drawings illustrate one complete example of thephysical embodiment of the invention, constructed according to the bestmode so far devised for the practical application of the principlesthereof, and in which:

FIGURE 1 is a vertical sectional view through an engine equipped withthe carburetor of this invention;

FIGURE 2 is a separated perspective view of the carburetor, a portion ofthe fuel tank on which it is mounted, and the air cleaner;

FIGURE 3 is a perspective view of the assembled carburetor, but with theair cleaner omitted;

FIGURE 4 is a fragmentary perspective view illustrating a detail of theignition grounding switch of the engine, with the various parts shownseparated fromone another; and

FIGURE 5 is a top view of the carburetor and adjacent structure, butwith the air cleaner removed.

Referring now particularly to the accompanying drawings, the numeral 5indicates generally the main body of the engine which preferably is adie casting such as that of the Lechtenberg Patent No. 2,693,789. Hence,the main body casting forms all but one of the walls of the crankcaseand also the finned cylinder 6. The open side of the crankcase, in thevertical shaft engine shown in FIG- URE l, is closed by a cover casting7 which has the mounting flange 8 of the engine formed thereon and whichalso provides an oil sump for the crankcase and contains the lowercrankshaft bearing (not shown). This lower bearing and another upperbearing also not shown, in the top wall of the crankcase, rotatablymount the crankshaft 9 of the engine, one end portion of which projectsdownwardly beyond the mounting flange to have the cutter blade of amower or other instrumentality to be driven secured thereto.

The outer end of the cylinder 6 is, of course, closed by a cylinder head(not shown) which is secured in place by bolts or capscrews 10. As iscustomary, both the cylinder and the cylinder head have heat dissipatingfins thereon.

The upper end of the crankshaft has a flywheel 11 fixed thereto whichalso serves as the rotor of the engine magneto, indicated generally bythe numeral 12. Air

propelling blades 13 on the upper face of the flywheel provide an airimpeller or blower capable of delivering a substantial flow of coolingair for the engine. Duct means indicated generally by the numeral 14directs the cooling air transversely across the finned cylinder 6 andcylinder head.

A rewind-type rope starter indicated generally by the numeral 15 ismounted on the shroud and connected in the customary manner with theupper end of the crankshaft to provide means for starting the engine.

The engine is of the L-head type and, hence, has intake and exhaustports 16 and 17 in its cylinder casting. These ports are spaced apartlengthwise of the crankshaft axis with the intake port 16 nearest theair impeller or blower. As is customary, the ports open to valve seats18 and 19 in the top or outer face of the cylinder casting, and withwhich the intake valves 20 and 21 coact in the customary manner.

It is significant to note that the intake port 16 opens toward that sideof the cylinder which faces the impeller or blower, i.e. upwardly in thecase of the vertical shaft engine shown in FIGURE 1; and that theexhaust port 17 opens laterally or horizontally away from the cylinder.

A muffler 22 is bolted to the cylinder casting over the mouth of theexhaust port 17. This muffler is of novel construction and forms thesubject matter of a copending application, Serial No. 233,005, filedOctober 25, 1962.

At the side of the cylinder opposite that at which the intake andexhaust ports'are located, is a fuel tank 23 and the improved carburetorof this invention, indicated generally by the numeral 24. The fuel tank23 has a generally oblong or rectangular shape and is mounted directlyalongside the cylinder crankcase casting with its top wall 25substantially in line with the upper side of the cylinderor, morespecifically, the cooling fins on the cylinder, as clearly seen inFIGURE 1.

The tank 23 is secured in position by means of suitable mountingbrackets, spot welded to the opposite ends of the tank, and bolted tothe crankcase cylinder casting.

Since the mounting brackets are spot welded to the opposite ends of thefuel tank, the points of securement of the tank to the engine arerelatively Widely spaced, and

being as firmly anchored as they are, it follows that there is nolikelihood whatsoever that the fuel tank will work loose as a result ofengine vibration. Also, since the carburetor 24 is mounted upon the topwall 25 of the fuel tank by means of a relatively large flange 26, thebottom face of which seats squarely upon the top wall 25 of the tank,utmost assurance is had against loosening of the carburetor. The flange26 may be secured to the top wall of the tank in any suitable way, as bycap screws 27.

The carburetor is of the type disclosed in the Brown et val. Patent No.2,529,242. Hence, it has a die cast tubular body 28 which provides amixture passage 29 in which the fuel and air is admixed and from whichthe fuel-air mixture issues for delivery to the intake port, and has theflange 26 formed integrally therewith. The fuel is drawn into themixture passage 29 by engine suction through .a'suction tube 36 whichprojects per-pendicularly from the bottom of the carburetor mountingflange 26 into a cup or reservoir 31in the upper portion of the fueltank. The fuel delivered by the suction tube 3% enters the mixturepassage of the carburetor through jets (not shown) under the control ofa needle valve 32 in the customary manner.

The cup or reservoir is kept filled with fuel from the fuel tank by anengine-suction actuated diaphragm pump 33, which is mounted on the sideof a carburetor body opposite its needle valve, and the inlet of whichhas a suction feed tube 34 connected thereto to project down y 195.5 K.A. w. KEMP 3,

E MP3 FOR INTERNAL COMBUSTI N fig 4. 10

July 13, 1965 K. A. w. KEMP 3,194,225

LIQUID FUEL INJECTION PUMPS FOR INTERNAL COMBUSTION ENGINES Filed May19, 1964 4 3 Sheets-Sheet 5 17 jig Z5 21 E 19 1% a Q 2? 45 I 44 59 s I Z4 United States Patent 3,194,225 LIQUID FUEL INJECTION PUMPS FORINTERNAL COMBUSTION ENGINES Kenneth Albert Walters Kemp, Ealing,Middlesex, England, assignor to C.A.V. Limited, London, Engiand FiledMay 19, 1964, Ser. No. 368,593 Claims priority, application GreatBritain, May 24, 1963,

, 20,770/63 4 Claims. (Cl. na -139 This invention relates to liquid fuelinjection pumps for supplying fuel to internal combustion engines and ofthe kind comprising a plunger mounted for reciprocation within a bore,actuating means for moving the plunger towards one end of said bore intime relationship with the engine with which the pump is associated todischarge fuel from said one end of the bore to an engine cylinder, anaxially movable shuttle mounted within a cylinder, a distributor memberarranged to be moved in synchronism with the engine, ports in thedistributor member for directing fuel from a source of fuel, at apressure dependent on the speed of the engine, alternately to oppositeends of said cylinder to move the the shuttle axially in oppositedirections, further ports in the distributor member whereby the fueldisplaced by the shuttle from one end of the cylinder will be fed tosaid one end of the bore to move the plunger axially, and a throttlearranged to control the quantity of fuel delivered from said source tothe cylinder.

The object of this invention is to provide such a pump in an improvedform.

According to the invention in a pump of the kind specified the movementof the shuttle towards the other end of the cylinder is limited by amovable stop member which is arranged to-be moved in accordance with thepressure of fuel delivered from said source, the arrangement being suchthat, as the speed of the engine changes the stop member will be movedto vary the permitted stroke of the shuttle thereby varying the maximumamount of fuel which can be delivered by the pump to the engine.

In the accompanying drawings:

FIGURE 1 is a sectional side elevation of one example of a liquid fuelinjection pump in accordance with the invention,

FIGURE 2 is a sectional view taken on the line 22 of FIGURE 1,

FIGURE 3 is a sectional view taken on the line 33 of FIGURE 1,

FIGURE 4 is a sectional view taken on the line 4-4 of FIGURE 1,

FIGURE 5 is a sectional View taken on the line 5-5 URE 2, and

FIGURE 7 is a view similar to FIGURE 1 with parts of the pump omittedand taken on the line 7-7 of FIG- URE 2.

Referring to the drawings, there is provided a body part 10 in which ismounted a rotary distributor 11 adapted to be rotated in timedrelationship with the engine with which the pump is associated. Mountedon one end of the distributor 11 is a feed pump 12 having a fuel inlet13 and a fuel outlet 14 in the body part these being interconnected by arelief valve, 15 which controls the outlet pressure of the feed pump ina manner such that the pressure is dependent upon the speed of theengine. The inlet 13 is arranged in use to be connected by way of apassage 13a to a source of fuel (not shown).

At the other end of the distributor 11 is a rotary head 16 in which isformed a transverse bore 17 containing a pair of plungers 18 which arearranged to be moved inwardly, as the head rotates, by a pair of rollers19 respectively which co-act with a surrounding annular cam 20 mountedfor limited angular movement within the body part iii. Within thedistributor is a longitudinal passage 21 which at one end is incommunication with the bore 17 in the head and which at another point isin communication with a radial delivery passage 22 which is arranged tocommunicate in turn, as the distributor rotates, with a plurality ofequi-angularly delivery ports 23 formed in the body part and incommunication with the cylinder of the engine respectively. At anotherpoint the longitudinal passage is in communication with the inner endsof a plurality of equi-angularly spacedradial inlet passages 24, equalin number to the number of delivery ports 23. Also formed in the bodypart are a pair of cylinders 25, 26 which contain a pair of reciprocableand close fitting shuttles 27, 28 respectively. The cylinder(hereinafter termed the main cylinder) is of larger diameter than theother and the cylinders have their inner ends terminating in a pair ofports 29, 30 respectively which are arranged to be placed incommunication with the longitudinal passage 21, at the same time, by wayof a pair of said inlet passages 24 respectively.

In the periphery of the distributor, intermediate the inlet passagesrespectively, is formed a plurality of longitudinal grooves 31. Thesegrooves are in communication with a circumferential groove 32 in thedistributor which is supplied with fuel from the outlet 14 of the pumpby way of an adjustable throttle valve 33 mounted in the body part.Moreover the grooves are arranged to communicate with the ports 29, 30during at least part of the time when the inlet passages 24 are notincommunication therewith.

Also formed in the body part is a series of first transfer passages 34which are in direct communication with the outer end of the maincylinder 25 and which are arranged to communicate with the grooves 31during the time when the inlet passages 24 are in communication with theports 29, 30. A series of second transfer passages 35 is provided in thebody part which are arranged to communicate by way of a plurality ofequi-angularly spaced further grooves 36 in the periphery of thedistributor 11 with ports 37 in communication with the inlet 13 of thefeed pump 12.

The permitted outward movement of the shuttle 27 is limited by anadjustable stop 38 which is normally fixed once the pump has beenadjusted, whilst the permitted outward movement of the shuttle 28 iscontrolled by a stop which is movable in accordance with the outletpressure of the feed pump. This stop comprises a spring loaded cylindermember 39 which is mounted within 2 a cylinder 44) having one end incommunication with the feed pump outlet 14 and the other end, whichcontains the spring 41 of the member, in communication with the feedpump inlet 13 by way of a passage not shown. The portion of the member39 presented to the shuttle 28 is profiled to a convenient form as shownin the drawing so that as the fuel pressure applied to said one end ofthe member 39 increases the permitted outward movement of the shuttle 28will be reduced. The outer end of the cylinder 26 is arranged to be incommunication with the outer end of the cylinder 25 by way of a port 42and a passage 42a in the wall of the cylinder containing the member andthe arrangement is such that when the outlet pressure of the feed pumpis sufficient to move the member against its spring this port will beuncovered by the member to place the outer ends of the cylinders 25, 26in communication with each other. Moreover a transfer port 25a isprovided in communication with the outer end of the cylinder 26 and thisis arranged to communicate with the inlet of the feed pump, by way of agroove 36 V and a port 'at the same communicate with the inlet of thefeed pump,

The operation of thepump will now be described, as; suming thattheengine with which the pump is associated.

has been started. During rotationof the distributor 11 the plungers. 18a're'moved inwardly by their interaction with the annular cam 20 andfuelis displaced fromthe bore '17 along the longitudinal passage 21 andthe delivery,

passage 22toone of the delivery ports 23v and to an'engine cylinder. Atthe same time fuel from the feed pump passes by way of the throttlevalve 33, the circumferential groove 32 and a pair of. the longitudinal;grooves 31 to the 25,? 2 6 to move the shuttle's inwardly. At the sametime fuel will be displaced from the inner ends of the, cylinders andvWill flow via the ports 29, '30 a pair of inlet passages 24 and thelongitudinal passage 21 to the bore 17 to move the plungers-18outwardly. This cycle is repeated as the distributor in turn.

. When theuengine is' atirest the outlet pressure of the feed pumpWillbe Zero and the spring loaded cylindrical member 39 will have beenmovedby its springlto a position in which the port 42 in the wall of thevcylinder containing the member will be closed. During the first fewquently'fuel from the feed pumpisfed directly to'the' bore in the headduring the filling periods thereof and an.

excess quantity of fuel above the normal maximumuuantity of fuel willbefed to, the engine. As soon, as the 'speedof the engine increases thepressure offuel deliv.. ered from the feed pump will rise-and thecylindrical member39- willibe moved againstitsspring to openport42 andto place the outer end. ofthe cylinders 25, 26 in coma The movement ofthe mernber 39 will'cause the shuttle to be moved inwardly andmunication with each other.

the port 44a will be closed to reduce the quantity of fuel fed to theengine. Moreover as previously stated, as the speed of-theengine andpump increases then'the permitted outward movement f the shuttle 28 willbe reduced and hence the maximum quantity of fuel which may be deliveredto the engine will be reduced. a The annular cam is permitted limitedangularmovement to vary the timing of the'injection of fuelinto theengine and for thispurpose there is provided-,in the body part, acylinder 44 .which containsa spring loaded piston; 45 which is arrangedto be subjected to the outlet pressure of the feed pumplZ during thetime' when the plungers are. being moved outwardly by the flow of fuelinto the.

bore. This. is achieved by arranging that eachof the longitudinalgrooves 36, in turn,.bridges a pairot. ports, 46, 47 in the body part,port 47 being connected to the 7 cylinder; 44 by way of acircumferential groove 48 and passage 49 and the port 46 to the outletof the feed pump.

The pressure of fuel upstream of the'throttle 33 is de-' pendent;uponthe speed of the engine,-as previously stated, and alsozupon thesetting of the throttle which is dependent upon the load on'the engine vThe effect due to the latter is increased further by the provision of arestricted orifice rotates and fuel is fed to each engine cylinder timeas the transfer ports 35 inner ends of the cylinders 25, 26 to move theshuttles ou'twardly and fuel is displaced from the outer-. ends of thecylinders through transfer passages 35, grooves 36 to revolutions oftheengine the shuttle 28 will be moved I outwardly to its maximum extentaspermitted by an excess fuel recess 43provided in the cylindrical memberand r in this position an excess fuel port 44a in the .wall of thecylinder 26 is uncovered. This port is in open communh' 1 cation withthe circumferential groove 32 and consey 48in the outletlof-the feed'pumpffwhich creates a presi 'sure drop dependent upon the quantity ,offuel being delivered by the pump.v

Having thusdescribed my invention what Iolaim as new 4 and .desiretosecure by'Letters Patent'is: 1; Liquid: fuel pumping apparatus, forsupplying 'fuel "to an internal combustionengineandcomprisingyan'injection pump arrange d to be driven i n;tin;'1ed relationship I withtheienginqsaid injection .pump beingiarranged'dur- I .-ing a pumpingstroke to deliver f u'e l to the engine, a'feed pump for providingfu'elunder pressurg valve nieansifo'r' 1 controlling the output pressureof ,'sa idj. feed-;pump" inla; manner which .varie s as the speed ofitheengine, an axially movable; shuttle contained within acylinder, adistributor member arranged to' be i driven :in i sync hronism with ther injection pump, passagesjin the jzli stribut'or forf'dir'ecting'fuel'from said feed pump-to opposite ends of: said cylin derin turn,thereby causingsaidshuttle to:be moved axial ly therein, furtherpassages in thedistributorarranged so 7 that fuel displaced frombne endof, said cylinder-will.

passto the injectionpuinp during a if llingtst roke thereof, Vj anaxially movable stop for limitingjthemovement of said shuttle away from'said'one end of the cylinder, thezface I of-said stop against which theshuttle bears .being inclined' 7 so that as thestop isi'mo'ved axiallythe; amount by which a the shuttle, can move away from; said one end ofthe cylin der will be;varied,,a condnitlthrough which one end ofthe .7stop is exposed to the output pressure of the feedpump whereby the axialposition Lot-the stop .willbe, dependent upon the output pressure;ofisaid f eed .pumpirand resilient means for opposingthe movement ofsaid stop-by the pre's sure of fuel, whereby as tiles-pressure of fueldelivered by;

said feed pump varies 5011116 permitted excursionZof the shuttle will bevariedzto vary the amount of fuelwhich' can be delivered to the engine;

zfLiquid fuel u i gapp r turqr uri iy i m an internal combustionengine'a nd comprising, aninjecs tion pump arranged tohe drivenintimed'relationship with1 the .engine,said injection pump beingarranged duringa pumping stroketo deliver fuelato'theengine,;a'-feed-pump for providing fuel; under 5 pressure, valve means forcon-j trolling the output pressure'offsaid feed pump in 'a'mane nerwhich varies as the :speed'-.,of the engine, an axially; i movableshuttle contained within aicylinder, {a distributor 1 member arranged tobe: driven in synchrfonism with the injection z'pump, passages .in V thedistributor for directing i a fuel fromsaid feed pump toopposite'endso'f saidcylinden in turn,-thereby causing said shuttle to be movedaxially therein, further-passages inthedistribntor'arranged so thatfuehdisplaced from "oneend ,of the cylinder: willapass to, V

the injection} pump duringafilling stroke. thereof, anaxial-i 1y,movable stop for limiting the movement ofsaid shuttle away from, saidone end of the cylindenithe-face of said;

stop against which the shuttle bears beingiuclined so that as the stopis moved axially. the amount I bygwhich the: shuttle can move awaytromsaid one end, dfithecylinde'r;

will be varied, agconduitthroughwhich one endfof the:

' stop is exposed to the output pressure of the f eed-pump. whereby the;axial position of thejstop will bexdependent 1 uponthe outputipressureof saidifeed pump and-resilient, means for opposing the; movement ofsaid stop by the pressure-of ,fuel, wherebyasthe pressure of fueldelivered by said feed pump varies .350 the permitted excursion of; theshuttle will bevaried to; vary the amount of fuelwhich f can bedelivered to the engine, airecess formed in .said. face'of said stopsaid recess bein'grpositioned 'so that, when the fuel pressure deliveredby said feed pump is below a r predetermined .value,lthe shuttle, can 7enter said recess, a

port in the wall of said cylinder, said port beingarranged] 'to beuncovered by said shuttle when the latterenters said;

, recess; a 'further,conduitithrough which the port'is in:

communication awith' theoutlet of;the feed pump so that during thefilling stroke of the injection pump fuel willbei' fed directly thereto,and valve means operableibysaidf cylinder whilst the pressure of fueldelivered by said feed pump is below the predetermined value.

3. Liquid fuel pumping apparatus for supplying fuel to an internalcombustion engine and comprising, an injection pump arranged to bedriven in timed relationship with the engine, said injection pump beingarranged during a pumping stroke to deliver fuel to the engine, a feedpump for providing fuel under pressure, valve means for controlling theoutput pressure of said feed pump in a manner which varies at the speedof the engine, a pair of axially movable shuttles contained within apair of cylinders respectively, a distributor member arranged to bedriven in synchronism with the injection pump, passages in thedistributor for directing fuel from said feed pump to opposite ends ofsaid cylinders in turn thereby causing said shuttles to be moved axiallytherein, an adjustable throttle member for controlling the quantity offuel supplied to said cylinders from said feed pump, further passages inthe distributor arranged so that fuel displaced from one end of saidcylinders will pass to the injection pump during a filling strokethereof, an axially movable stop for limiting the movement of one ofsaid shuttles away from said one end of its cylinder, the face of saidstop against which the shuttle bears being inclined so that as the stopis moved axially the amount by which the shuttle can move away from saidone end of the cylinder will be varied, a conduit through which one endof the stop is exposed to the output pressure of the feed pump wherebythe axial position of the stop will be dependent upon the outputpressure of said feed pump, and resilient means for opposing themovement of said stop by the pressure of fuel, whereby as the pressureof fuel delivered by said feed pump therein so the permitted excursionof the shuttle is varied to vary the amount of fuel which can bedelivered to the engine, a recess formed in said face of said stop, saidrecess being positioned so that, when the fuel pressure delivered bysaid feed pump is below a predetermined value, the shuttle can entersaid recess, a port in the wall of said cylinder arranged to beuncovered by said shuttle when the latter enters said recess, a furtherconduit through which the port is in communication with the outlet ofthe feed pump through said throttle member so that during the fillingstroke of the injection pump fuel will be fed directly thereto, andvalve means operable by said stop to prevent the flow of fuel to theother end of the cylinder whilst the pressure of fuel is below saidpredetermined value.

4-. A pump as claimed in claim 3 including a pressure operable pistoncontained within a cylinder for determining the timing of injection offuel to the engine by said injection pump, a restriction intermediatethe outlet of said feed pump and said throttle member, a conduitinterconnecting one end of said cylinder containing the fluid pressureoperable piston and a point intermediate said restriction and saidthrottle member and valve means constituted by said distributor wherebycommunication between said point and said one end of the cylinder isestablished only during the filling strokes of the injection pump.

References Cited by the Examiner UNITED STATES PATENTS 3,025,797 3/62Hutcheon l23139 10/63 Kemp l23139

1. LIQUID FUEL PUMPING APPARATUS FOR SUPPLYING FUEL TO AN INTERNALCOMBUSTION ENGINE AND COMPRISING, AN INJECTION PUMP ARRANGED TO BEDRIVEN IN TIMED RELATIONSHIP WITH THE ENGINE, SAID INJECTION PUMP BEINGARRANGED DURING A PUMPING STROKE TO DELIVER FUEL TO THE ENGINE, A FEEDPUMP FOR PROVIDING FUEL UNDER PRESSURE, VALVE MEANS FOR CONTROLLING THEOUTPUT PRESSURE OF SAID FEED PUMP IN A MANNER WHICH VARIES AS THE SPEEDOF THE ENGINE, AN AXIALLY MOVABLE SHUTTLE CONTAINED WITHIN A CYLINDER, ADISTRIBUTOR MEMBER ARRANGED TO BE DRIVEN IN SYNCHRONISM WITH THEINJECTION PUMP, PASSAGES IN THE DISTRIBUTOR FOR DIRECTING FUEL FROM SAIDFEED PUMP TO OPPOSITE ENDS OF SAID CYLINDER IN TURN, THEREBY CAUSINGSAID SHUTTLE TO BE MOVED AXIALLY THEREIN, FURTHER PASSAGES IN THEDISTRIBUTOR ARRANGED SO THAT FUEL DISPLACED FROM ONE END OF SAIDCYLINDER WILL PASS TO THE INJECTION PUMP DURING A FILLING STROKETHEREOF, AN AXIALLY MOVABLE STOP FOR LIMITING THE MOVEMENT OF SAIDSHUTTLE AWAY FROM SAID ONE END OF THE CYLINDER, THE FACE OF SAOD STOPAGAINST WHICH THE SHUTTLE BEARS BEING INCLINED SO THAT THE STOP IS MOVEDAXIALLY THE AMOUNT BY WHICH THE SHUTTLE CAN MOVE AWAY FROM SAID ONE ENDOF THE CYLINDER WILL BE VARIED, A CONDUIT THROUGH WHICH ONE END OF THESTOP IS EXPOSED TO THE OUTPUT PRESSURE OF THE FEED PUMP WHEREBY THEAXIAL POSITION OF THE STOP WILL BE DEPENDENT UPON THE OUTPUT PRESSURE OFSAID FEED PUMP AND RESILIENT MEANS FOR OPPOSING THE MOVEMENT OF SAIDSTOP BY THE PRESSURE OF FUEL, WHEREBY AS THE PRESSURE OF FUEL DELIVEREDBY SAID FEED PUMP VARIES SO THE PERMITTED EXCURSION OF THE SHUTTLE WILLBE VARIED TO VARY THE AMOUNT OF FUEL WHICH CAN BE DELIVERED TO THEENGINE.